1. Field of the Invention
This invention relates generally to systems for performing spinal fixation. The invention comprises one or more vertebral spacers that feature an attachment system that resists backing out of the screws used to attach the spacers to the vertebrae. The invention may be configured so that multiple adjacent spacers may be used along the vertebral column.
2. Description of the Related Art
Advancing age, as well as injury, can lead to degenerative changes in the bones, discs, joints and ligaments of the spine, producing pain and instability. Under certain circumstances, alleviation of the problems can be provided by performing spinal fusion. Spinal fusion is a surgical technique where two or more vertebrae of the spinal column are fused together to eliminate the motion between the fused vertebrae. Spinal fusion is used to treat conditions where the spine exhibits instability. Spine instability may result from causes such as fracture, scoliosis and spondylolisthesis, where one or more vertebrae move in a forward direction relative to the other vertebrae. Spinal fusion with discectomy is also performed for herniations of the discs. This surgery involves removal of the affected disc and fusion of the adjacent vertebrae. Traditionally, bone grafts have been used to fuse the vertebrae, but various types of vertebral implants have also been used.
The use of bone plate and bone screw fixation systems for treating injuries to bones is well established. In most instances, a bone plate is positioned over and surrounding the bone injury area and secured to the bone. The bone plate is secured to the bone by bone screws or other similar fasteners inserted through holes in the bone plate and into the bone itself. The screws are tightened so that the bone plate holds the bone to be treated in place in order to insure proper healing. Early fixation devices tended to be applicable only to long bone injuries with only limited uses for lower lumbar spinal injuries and disorders. The use of plate/screw fixation systems later expanded, however, to include more uses for spinal injuries, including fusion of vertebrae including fixation devices for treating cervical vertebrae injuries.
Notwithstanding the foregoing, there remains a need for improved methods and devices for treating spinal instability.